DESCRIPTION: (Applicant's Abstract) Increasing numbers of youth are infected with HIV & are confronted with a series of challenges: stopping HIV transmission to others, maintaining health care regimens, & improving their quality of life. Over the last 4 years, an intensive, 31-session, 3-module intervention was designed, implemented, & evaluated to help youth living with HIV (YLH) meet these challenges. YLH significantly changed behaviors; however, a restructuring of the intervention is required based on new information from our previous study & new scientific breakthroughs: 1) only 30% of YLH continue their substance use & sex risk after learning they are seropositive; 2) 30% of YLH never attended any group session; and 3) the recent scientific advances in HIV require addressing beliefs regarding post-exposure prophylaxis, life expectancies, undetectable viral loads, & the role of substance use in adhering to new medical regimens. Therefore, building on the positive results of the previous study, a secondary prevention program, CLEAR (changing Lifestyles: Effort And Rewards), will be evaluated over 21 months for 200 substance-using YLH (aged 13-23) in Miami & LA. The youth will be randomly assigned to a 3-module intervention (totaling 18 sessions) that is delivered in either: a) anonymous telephone groups or b) individual sessions. Based on the Social Action Model, the intervention will: 1) in Module 1, reduce substance use & sexual behaviors that may transmit or enhance transmission of the ~V virus; 2) in Module 2, reduce the negative impacts of substance use on seeking & utilizing health care, & increase assertiveness & adherence to health regimens; & 3) in Module 3, enhance quality of life & self-actualization in order to maintain behavior changes over time. In addition, we will examine I ) how YLH's substance use influences seeking & adhering to combination antiretroviral therapies, & youth's reinitiation of transmission acts based on their viral loads & beliefs regarding transmissivity of undetectable viral loads, as well as beliefs in post-exposure prophylaxis & life expectancies; 2) how well the components of the Social Action Model predict reductions in substance use, sexual behaviors, & relapse, & improvements in health adherence, acquisition of knowledge of the program, & quality of life; & (3) the cost effectiveness of delivering the prevention program to YLH, as well as monitoring costs for health utilization for medical & nonmedical services & differential benefits of telephone groups, individual sessions, & small groups (from previous study).